Effects of curvature-related DEM contact model on the macro- and micro-mechanical behaviours of granular soils

A comprehensive comparison between the Hertz–Mindlin model and the linear spring model in true triaxial shear simulations of granular soils was conducted using the discrete-element method (DEM). The no-slip Hertz–Mindlin model for general elastic non-spherical particles with smooth surfaces was revisited and implemented for superellipsoidal particles in an in-house DEM code. Three groups of specimens with a grain size distribution of Ottawa 20–30 sands, consisting of spheres, ellipsoids and superellipsoids, respectively, were subjected to triaxial shear DEM simulations with the Hertz–Mindlin model and the linear spring model. The corresponding mechanical behaviours were examined in terms of a series of macro- and micro-parameters. It was found that the linear spring model was able to resemble the Hertz–Mindlin model in aspects of both microscopic and macroscopic mechanical behaviours of granular media with spherical and/or non-spherical particles. This finding suggests that the linear spring model can be used to investigate micro-mechanical behaviours of granular soils, even with complex particle shapes.